It is desirable to trap evaporated fuel and oil vapors within the air intake system, thereby preventing their release into the outside environment. Hydrocarbon emissions from motor vehicles are known to be a significant contributing component in urban smog.
Gasoline, for example, is a highly volatile hydrocarbon fuel that includes components known to transition easily from a liquid to vapor phase. Elevated temperatures such as occurring during normal internal combustion engine operation accelerate this liquid to vapor transition. The hydrocarbon vapors, unless treated or captured, may ultimately discharge into the atmosphere. It is also known that hydrocarbon vapors are discharged from the engine crankcase during engine operation. When the engine is shutdown, these vapors may continue to be released from the hot engine crankcase and other components, particularly as the engine cools.
The control of hydrocarbon vapors escaping into the environment is regulated by state and federal regulations. Hydrocarbon traps for capturing hydrocarbon vapors are known. For example, motor vehicles are commonly equipped with hydrocarbon adsorptive emissions canisters connected to the fuel tank for trapping hydrocarbon vapors, particularly as emitted during refueling.
It is known that certain porous materials such as activated carbon are particularly useful for adsorption and removal of organic hydrocarbon vapors. It is known hydrocarbon vapors are liquefied within small micro pores of the activated carbon and may be retained therein by adsorption.
Varieties of flow-through types of hydrocarbon traps are known. As airflow must pass through restrictions in such flow-through traps, these traps present an undesired restriction to the airflow, resulting in an undesirable airflow pressure drop into the air intake tract.
U.S. Pat. No. 5,914,294 discloses a monolithic trap configured to adsorb chemical constituents from a gas stream. This is achieved by bringing the gas into direct contact with the activated carbon in the monolith. One disadvantage of this type of extruded or press formed hydrocarbon trap is that the extrusion and binding process results in a relatively brittle trap that may crack or have individual pieces splinter off.
Another example is U.S. Published Application 2005/0223894, which discloses an adsorption element for adsorbing gases and vapors from the intake tract of an engine. The adsorption element has free-flow channels in an element having a spacer layer and an adsorption layer. One disadvantage of this type of corrugated trap is that the trap itself introduces an unnecessary and undesirable restriction to airflow in the intake tract.
U.S. Patent publication 2011/0023719 discloses a hydrocarbon adsorption trap configured for installation into an air intake tract.
U.S. Patent publication 2011/0072974 discloses a flame retardant hydrocarbon adsorption trap.
As can be understood from the above, there remains a need in the art for a simple, low-cost hydrocarbon adsorption trap that is easy to assemble, rugged, and does not present a restriction to air flow in the air intake tract.